Giving us a reason to dust off our wallets this weekend, Valve has announced that Frictional Games' Penumbra Overture and Penumbra Black Plague Gold Edition are currently on sale through Steam at a 75% discount. You can buy them separately for $2.50 and $3.75 respectively, or grab both in a package for just $5.00. This hot deal runs from now until June 7th...so don't miss it! :D